SPID#: 62 Documenting the influence of housing condition on the well-being of captive primates is critical for guiding management decisions and facility design. This study contributes to our understanding of the behavioral consequences of two types of indoor housing common to biomedical research on chimpanzees housing in single cages and in small social groups of two to three individuals. Multiple measures of behavioral well-being were assessed from 132 hours of focal animal sampling of 23 singly caged and 13 socially housed chimpanzees. Analysis of variance revealed no sex differences in the behavioral categories analyzed. However, housing in single cages resulted in significantly lower inactivity scores and higher scores for the categories of environmental manipulation, locomotion, aggression to the observer, and tension-related behaviors. Singly caged subjects were significantly more reactive to others' displays than socially housed individuals. Abnormal behavior, affiliative observer-directed behavior, self-grooming, and temper tantrum scores were not significantly affected by housing condition. Housing tenure of three to nine years in the current study permitted a comparison of long-term effects of housing condition with previously published short-term effects; long- and short-term effects differed for several behavioral categories. Pair- and trio-housed individuals showed similar levels of well-being. Findings of this study may be useful for guiding enrichment regimens for chimpanzees housed in the conditions investigated here, and for determining the level of social complexity that will produce consistently positive effects on various measures of well-being.